[英]Issue with dynamically loading a user control on button click
我有一個頁面,其中動態加載用戶控件,如下所示:
Default.aspx的:
<cc1:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
</cc1:ToolkitScriptManager>
<asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
Default.aspx.cs:
protected void Page_Load(object sender, EventArgs e)
{
var ctrl = LoadControl("~/UserCtrl1.ascx");
ctrl.ID = "ucUserCtrl1";
PlaceHolder1.Controls.Add(ctrl);
}
下面是UserCtrl1.ascx的代碼
<asp:Label ID="Label1" runat="server"></asp:Label>
<asp:Button ID="Button1" runat="server" Text="Button1" OnClick="Button1_Click" />
<br />
<asp:PlaceHolder ID="PlaceHolder2" runat="server"></asp:PlaceHolder>
單擊Button1時,我正在動態加載另一個用戶控件
UserCtrl1.ascx.cs
protected void Button1_Click(object sender, EventArgs e)
{
Label1.Text = "UserControl - 1 button clicked!";
var ctrl = LoadControl("~/UserCtrl2.ascx");
ctrl.ID = "ucUserCtrl2";
PlaceHolder2.Controls.Add(ctrl);
}
以下是UserCtrl2.ascx的標記
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:Label ID="Label2" runat="server"></asp:Label>
<asp:Button ID="Button2" runat="server" Text="Button2" OnClick="Button2_Click" />
</ContentTemplate>
</asp:UpdatePanel>
UserCtrl2.ascx.cs
protected void Button2_Click(object sender, EventArgs e)
{
Label2.Text = "UserControl - 2 button clicked!";
}
在頁面加載后,當我單擊UserCtrl1中的Button1時,將觸發click事件,並且能夠看到Label1文本。 它還可以正確加載UserCtrl2,但是當我單擊UserCtrl2中的Button2時,單擊事件就會觸發,更糟糕的是,當我兩次單擊Button2時,該頁面上消失了UserCtrl2控件。 我怎樣才能解決這個問題?
第二個控件的問題是您僅在單擊按鈕1之后才找到它。但是,當發生其他一些(不是單擊按鈕1的)回發時,第二個控件將不會加載。
可能的修復方法之一是保存一些標志(例如,在ViewState中),該標志將幫助您確定是否應該加載第二個控件(並在頁面加載時加載)。
protected void Button1_Click(object sender, EventArgs e)
{
Label1.Text = "UserControl - 1 button clicked!";
var ctrl = LoadControl("~/UserCtrl2.ascx");
ctrl.ID = "ucUserCtrl2";
PlaceHolder2.Controls.Add(ctrl);
this.SecondControlLoaded = true; // This flag saves to ViewState that your control was loaded.
}
protected void Page_Load(object sender, EventArgs e)
{
var ctrl = LoadControl("~/UserCtrl1.ascx");
ctrl.ID = "ucUserCtrl1";
PlaceHolder1.Controls.Add(ctrl);
if (this.SecondControlLoaded)
{
var ctrl = LoadControl("~/UserCtrl2.ascx");
ctrl.ID = "ucUserCtrl2";
PlaceHolder2.Controls.Add(ctrl);
}
}
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